1. Field of the Invention 
This invention is generally directed to devices for use in preventing unauthorized access to hitches of the type which are used to receive a pintle of a towing vehicle and which are often associated with heavy duty trailer type equipment used in construction and in maintenance. More particularly, the present invention is directed to a protective device which functions to seal off a hitch ring of a trailer device so that it can not be towed by unauthorized personnel and wherein the device is locked to the hitch ring in such a manner that unauthorized tampering of the lock, shackle or bolt is prevented. 
2. Description of the Related Art 
Equipment used in the construction and maintenance industry is frequently mounted on a trailer to promote portability. Many such heavy duty type trailers utilizing a  hitch which is adapted to be mounted to a tongue of a towing vehicle by way of a pintle which extends through an opening in a circular ring or hook type device defined by the hitch. 
It is often not possible to leave or store such trailers or trailer mounted equipment in secured areas. Often, it is necessary that such equipment and trailers be left on site and, unfortunately, such equipment and trailers are subject to misappropriation or theft. 
In an effort to deter the unauthorized use or theft of such trailers and equipment, there have been a number of innovations directed to devices for securing such trailers and equipment by preventing the use of the hitch assemblies associated therewith. By way of example, heavy duty chains are often passed through a hitch rings and locked upon themselves in order to obstruct the opening through the hitch rings. Unfortunately, such chains and the locks used to secure them are subject to tampering using bolt cutters and other devices. 
Other protective devices include assemblies which are designed to be mounted within a hitch ring and secured utilizing conventional locks. However, in many such assemblies, the lock bolt or lock shackle may be easily  accessed so that the shackle or bolt can be tampered with utilizing bolt cutters or other tools. 
Some examples of prior art type protective devices for pintle hitch assemblies are disclosed in U.S. Pat. No. 4,186,575 to Bulle; U.S. Pat. No. 5,343,720 to Slater; U.S. Pat. No. 4,480,450 to Brown; U.S. Pat. No. 5,332,251 to Farquhar; and U.S. Pat. No. 4,380,160 to Hoffman. 
In view of the foregoing, there remains a need to provide for a protective device which may be secured to a hitch adapted for use with the pintle of a towing vehicle wherein the assembly provides a secure housing for a lock such that the lock can not be tampered with utilizing bolt cutters and other tools which could be used to otherwise circumvent the protective device. 